£300 ish to spend

[Angelfishsolo]

That does of course assume that the OP can afford two sets of wheel and tyres. I would go for a trail tyre. Great on road and adequate on all but the most technical of MTB routes.

If your running discs and QR then changing a wheel is a 20 seconds job, so run a pair of semi slicks and a pair of knobblies when going proper off road....or choose off road tyres with a solid centre ridge, not the very best off road, but work OK!

Riding a Giant Rincon with lockout front sus and front disc (rear disc conversion started)....2 sets of wheels/tyres.

Simon