if you dont sign on apart from the little bit of benifit money you dont get, you also do not get your national insurance stamp credit. This is worth getting out of bed for in the long term.
ye know that not out of work long catch up from wages?
Yes, you catch up from your wages when you restart work. Most likely on an emergency tax code. You'll end up paying more NI (and possibly income tax) than you require to make up the deficit, but without proof that you were unemployed you'll have difficulty getting a rebate.
Worth noting, it's not unheard of for people to receive an NI invoice from the tax office when they've not been signing on but have been out of work (especially when it takes a while longer than they thought to get work).