Theres not a whole lot to do in south east england to be honest (where I am
I'd ignore that statement if I were you theres a load of good riding in the South East of England
Ok so there no mountains (But Lets face it we dont have mountains in England just Big Hills ) - but there is plenty of sweet singletrack if you know where to find it
If you want a guide to some of the best rides on the South Downs (I live near Brighton), and the best trails on the Surrey Hills (Just south of London) - let me know
I might even be able to persuade my wife to put you up for a couple of nights if you do decide to ride down our way
I'll be visiting the USA my self this april - I'm currently planning on being in Moab on 24th & 25 April before hitting Fruita for a couple of days and then over to St George before flying home from Las veags on 1st of May - But i see Orem is miles away from any of the places I riding
heres a few pics from around where we live to give you an idea whats it like south downs = rolling hills - with singletarck hidden away in pockets of wood land, surrey hills = hilly woods bursting at the seams with singletrack goodness
Make sure you get up to the lake district though thats were some of our most seanic trails are at , the welsh trail centers are ok but you tend to just get views of wall to wall conifers and end up doing a lot of ridig on fire roads to get to the single track. But if I'm being very honest I'd rather be riding the deserts of South West USA myself - but as you visiitng our fair wet isle I'm sure the radical difference will mean you'll enjoy everything we have to offer
As others have said
1) Gas is expensive - if you do rent a car make sure its a desiel to get mosty miles per gallon
2) Our roads are rubbish - it will take you ages to get any where
3) Public transport imho is also rubbish - you are better off with your own vehicle
Other places that would be good to ride at would be Exmoor & the Quantocks (Somerset) and Dartmoor (Devon)
Cheers
Zinger