If you're not going to be flying for 48 weeks of the year, which aircraft will you be doing it in?
Are you looking to buy one?
Or you'd need to join a group which was happy to let you monopolise the plane for a full fortnight twice a year (doesn't sound much, but if there are a few active flyers in the group it needs to be properly handled/scheduled). And even then, you'd have a capital cost up front and a monthly (plus be liable for a cash call) even when not flying.
So that leaves renting. If you've not flown for 6 months, whoever you rent off of will want you thoroughly checked out - so there's a few hours with an instructor. But you might have issues getting availability with a rental unless they have available aircraft.
You could likely do it in the US where there's more rental/touring capacity, but in the UK, and with the weather, it'd likely be virtually impossible to notch up 20 hours in two weeks in an aircraft you don't own at least a part of.