Another vote for the Fas from me. Probably the best over lever pnuematic made and far far superior to the compact and the HW40. I do have a 604 for sale on behalf of a member of the club where I coach. PM if interested.
A word or warning with the HW40 (oh and true glows are not allowed in ISSF competition), on occasions I have noticed a prominant muzzle flip when being used by shooters with a light grip (which you should be using anyway) and in particular kids and ladies. It would only really be an issue paper punching, but it will and does affect accuracy.
The Compact is the best all round starter match pistol but may need some work to the grip and a good polish of the sears to improve it.
My advice whilst not diminishing what others like Derek and Nige have posted would be to go for a compact, 604 or the Alpha to start you off, then as funds become available, an LP2 Junior although Walther also do a junior version which is worth looking at.
Finally the Rohms (the fact that there have been very few replies might be worth considering). Great for general shooting and fun but they have two major draw backs for serious 10m which are a fiddly single shot magazine and a slow lock time due to the hammer having to strike the release valve. Neither of these are helpful in competition.
Good luck.
Bob