The engine is a 150cc Mk12C Villiers manufactured 1932-40. Quite possibly the engine number could tell us more as Villiers would use a unique identifying prefix for anyone who talked nicely to them and was buying in quantity.
The front forks are normal pressed steel Webbs, available from the early 30's on many lightweights right up to a last gasp on Ambassadors in the early 50's. They are a heavier duty version of those shown on the Waratah. They work surprisingly well for what they are.
The gearbox is an Albion but not enough is shown to say exactly which one or whether 2 or 3 speed. If you were remarkably lucky it could be 4 speed.
The headlight appears to Lucas. Its definitely not Villiers although its easy enough to wire in.
The frame number could tell us more.
Off hand the only British lightweight with a pressed steel frame I can think of is the Coventry Eagle but that doesn't look Cov Eagle to me. I don't think it is European as the engine, gearbox, forks and wheels are all standard English stuff.
Unless you have a well equipped machine shop/workshop stay away from it. Except for the engine there are virtually no spares available for this type of bike. You have to either make it yourself or pay someone else to. If you have the right trade skills they are a cheap and simple restoration. If you are the average punter they are expensive to restore with a low value when you've finished.
What's it worth? Very little as is but that won't stop someone from buying it for more than its worth. Worth also depends on what country you live in.
Have a nice day.