I have recently visited Preston and popped into the open mat at Falkie Brazilian Jiu Jitsu and I can't recommend it enough. The gym is run by a father and son, and it's absolutely obvious that BJJ is their life and passion. They welcomed me in and we had a great workout. All the students there were great and friendly and really made me feel welcome.
If you're looking for a jiu-jitsu gym and you live in and around Preston then this is the spot you want to be training.