It depends what type of orbit you want to enter. If you launch from a high latitude, and thrust directly East, then you end up with an orbit that has a declinat

It depends what type of orbit you want to enter. If you launch from a high latitude, and thrust directly East, then you end up with an orbit that has a declination that brings you back to that same latitude. You can increase the orbital declination by thrusting in a different direction than pure East, but it isn't possible to decrease the declination without effectively turning a corner over the equator. Turning a corner in orbit takes a huge amount of delta-v, making the rocket much bigger and more expensive. Therefore, the UK is not a sensible place to launch from if you want an equatorial orbit, but it's fine for a polar orbit.