As thetford is my local I will review that.

Trails- At thetford there is a black and Red trails along side other family cyle trails.
Due to erosion from previous winters they are in a bad shape. The red is currently being worked on by Timber which are doing a great job of sorting them out. Up till recently they have been doing most of the work by themselves so it has taken along time to get the sections of trail all surfaced but with new funding on the horizon FC are willing to put more money into the trails than previous which is great news for biking in thetford. The grading at thetford may be different than other places in the Uk this will be because it is flat which some people think it makes it easier. But at thetford the faster you go the more challenging the trails become so it is down to how fast you can go. For what thetford lacks in gradient it makes up for in quantity of flowing singletrack.
But if you find yourself becoming bored at thetford the beauty of the place is that you can go explore the forest and see if you can find any "off piste" trails the most well know part of thetford for this is brandon country park side of thetford.

Centres- The centre at theford is not specifically set out for biking. There is a restaurant that serves great food and a FC run shop. Adjacent to this building is the bike shop called Bike art who do bike hire as well as sales. All the toilets have underground heating so are nice and warm on the feet even in the coldest of months. In the summer if you are with other famaily members who want something to do that is adventurous try Go Ape which is a high wire adventure course.
For more information about Thetford Forest and High Lodge and what to do, go have a look at the Forestry Commission's website

May be a few spelling grammar in there.