This does strike me as a bit more than post skills test nerves (which are normal). Stapleford has clear airspace to the east. Go back to basics and plan a route to say Southend, Clacton and up the coast. Practice tracking the Clacton VOR out and the Satpleford on the way back in. Plan and make a few short land aways. You have Clacton, Andrewsfield, Earls Colne, Elstree, Southend, Rochester, Headcorn and Biggin in easy reach. If you dont want to land away then there are many local features you can use to plan and test your local navigation. It is surprising how quickly you will become familiar with the local area and learn to identify features.
Coming back to Stapleford should not be a problem if you are coming back on an east west line (London City is 6/7 miles to the south and needs watching).
For further afield try an excursion into deepest Norfolk, where there is lots of uncontrolled airspace and some nice airfields to visit.
With 15 hours only P1 you need more solo time. There is no substitute and the problem with always having the more experienced guy in the right seat is that you will tend to look to him for decisions or defer to him. The first time solo from a new field will be daunting, but when you get back it will feel great. You would not have gone solo, done your navx and passed your GFT if people did not think you were up to it
