Good advice so far, I would only add that your budget is reasonable and so it pays in your case to buy a few quality items to begin with and add to it as experience and time allows.
On that basis I would take as a starting point what actually needs to be done to reload a cartridge.
The stages of reloading a case are the following:
- deprime case
- clean case (optional)
- resize case or case neck
- trim case
- reprime case
- charge case with powder
- seat bullet
- crimp bullet (optional)
For example, I started with a Lee hand press and loaded many rounds with it.
I broke it trying to FL size 2006 brass and so got a RCBS rockchucker which will probably be passed onto my grandchildren one day. I did buy another Lee hand press but for different reasons ( loading on the range) but had I bought the RCBS in the first place it would have been a case of buy once cry once.
My advice is therefore to first buy a good single stage, cast press such as the Lee classic cast for around £150 to the RCBS rockchucker supreme at around £200 with the Hornady and Lyman offerings falling in between in terms of cost. I personally prefer RCBS but there is no real difference in quality between these brands, see what your local gun shop has or find the best offer on line. These presses all allow for depriming as well as repriming on the press using little attachments and whilst this method is a little slower than a dedicated hand priming unit works very well and is perfectly adequate for the beginner; With a £15 Lee universal decapping die and £5 calibre specific shell holder bought at the same time the press therefore takes care of 1. (and 5.)
That leaves around £280-330 left of your budget and the empty cartridge case has been deprimed and is ready for sizing.
A word on cleaning, it is not necessary to get the inside and out of your case spotless but for the sake of your reloading dies cleaning the outside of the case will prevent scratches on the precision surface in the die and cleaning the primer pockets will give you consistency in primer seating depth. This can be done without fancy equipment, a bit of 0000 wire wool on the outside of the case and gentle scrape with a small screwdriver in the primer pocket will do the job; save the money here until you have the more important bits in my opinion.
To do this you need a set of dies, at a minimum a Full Length sizing die and a bullet seating die. It is nice to have a neck sizing die and a crimping die also but not to get started and these can be added on later when funds and experience allow.
Dies sets range from £40 for Lee 3 die sets to over £200 for Forster competition sets but luckily the differences are not very relevant for the beginner and the Lee deluxe set is the one to go for in your shoes. You also need some case lube to stop the cases getting stuck in the dies and I would recommend Imperial die case sizing wax as the best of the best at £5 for a small tin which will last for years.
This brings the budget to £235-285 and you have have a deprimed and sized case for your troubles.
You need to trim your cases now, particularity if you have been following everyone's advice and FL sizing. Trimming promotes consistency and not trimming can result in severe overpressure problems.
The cheapest and easiest way to trim cases is with the Lee trimming kits you use an electric screwdriver for being the "Lee Precision Case Trimmer Cutter & Lock Stud" and the calibre specific "Case Length Gauge & Shell Holder" for your .223 at around £15 total.
The good thing about these items are they are cheap, consistent and you don't need to measure the case every time as it trims them all to the same length.
Clean the lube off the case and from he inside of the neck with kitchen towels, cotton buds and meths and reprime using the press.
Your budget is now £220-260 and you have a case that is the equivalent of a new, unfired case ready for charging, seating a bullet on and firing.
As everyone has said, you need good, repeatable scales to charge your cases. I recommend some dampened balance beam scales such as the RCBS 5xx series, with the 505 being about the best for the money. Avoid the Lee scales as being undampened they take ages to settle. These will set you back around £100 and you have a case ready for seating the bullet and a budget of £120-£160 left. Parabueto explained why avoiding cheap electronic scales is a good idea.
The dies and press do the work of seating the bullet but you will need a a decent set of vernier calipers to measure the overall length of the rounds you are producing and to keep that measurement the same between reloading sessions. These are can be had from about £25 quid up and I would get one that reads in Imperial units if dedicated to reloading.
At this stage and with around a hundred quid left of your budget you have produced a round of ammunition that is much more consistent than factory ammunition and done it with quality kit that you will never need to sell to "upgrade", you simply add more kit to it as funds and experience allow.