Personally, I'd get a license and carry on, however much I object to airgun licensing because I see it as the thin end of a very large wedge.
However, I believe that licensing is simply not practical in England because there must be millions of forgotten or hardly ever used airguns hiding in lofts, sheds, & at the back of cupboards, plus there are a huge number of airgun owners who are "out of the loop", unaware that there are airgun ranges, organised competitions, and forums where they can engage with other airgun shooters, so they have no idea that there might be a threat to airgun ownership.
It would be deeply unfair to punish these people for unknowingly breaking the law by not obtaining a license, ignorant of a new change in the law regarding something they've perhaps done legally for a long time.
As the government don't seem to to do "Public Information" films any more I doubt we'd see a campaign to advertise a new law requiring airguns to be either licensed or handed in, and as the work of simply policing the streets properly appears to be beyond the resources of our police forces I doubt very much that they would be able to cope with the workload of licensing huge numbers of airgun owners.
I suspect that the only practical way to impose licensing would be to demand that a license be required for the purchase of a new airgun, to shoot at an established range, or to take part in competition such as HFT. The "back garden plinkers" that remainded unaware of licensing might be very gradually mopped up by their coming to the notice of the police, and given the choice of obtaining a license or forfeiting their guns. Even then, in rural areas where shooting is part of the fabric of society and out of sight of the public, you're unlikely to be "turned in" by a neighbour because they'd have to live with the consequences - hard to do when they might have to ask a favour of you someday.