Thomohawk, The back of the hotel has loads of short walking and 'outdoor pursuits' routes which are fun to explore in places (especially at night) but often overgrown on the singletrack front. They will link you to the main area of forest (where clear felling or council-sponsored road-building has removed most of the interesting singletrack). Just follow your nose and explore.
Most loops on the moors that would be obvious from here would use bits of singletrack that are prone to being boggy (or damage when this wet), and it isn't going to freeze this weekend, so like some of the others above I wouldn't recommend them now (unlike warton ). That said, decent out-and-back routes are possible that avoid this. You can cut the one described below short at every village and loop back on the back roads (which are great riding (for roads or road bikes – nice climbs, high-level cruising and fast descents, all quiet) or retrace your tracks.
For example... Using the hotel tracks loop around to the top of the forest. From there head west/south west to the main track over toBlanchland (big obvious gate- can't miss it). This will be messy in spots, but it is generally resistant to damage. Head south to the village. Pop into the Crewe (the crypt is pretty special). A quick spin (south) up the road towards Roohopewill bring you to the C2C route (almost the highest point of the road, head straight on on the very obvious left handed bend, ignore the track to the quarry on your right) which can be used as a high level (windy) route. It's an old railway track and all weather, but the descent down from the engine house torookhope can be insanely fast. From there, you can cross over (continuing same direction) to Weardale climbing on the road, descending on roughbyways (all obvious on the ground/ on the map).
IMO @ Kielder the best stuff is short sections of the black climbs- they really are pretty good compared to any trail centre climbs I've done. I always forget about them for some reason.