i wouldn't bank on jessops having anything.
My brother (new to medium format) went in a few weeks ago, and asked for some 120 - they confirmed they had "both kinds of film". He bought the entire stock - one roll of hp5 and one roll of fuji colour! He's based in Newcastle (sometimes), though it may not have been the newcastle store he was at on this occasion.
He did recommend MPS though - he's pretty new to this, but he took some E6 there for dev'ing, and said they treated him nice.
In a similar experience last year my gilrfriend needed 10 rolls of 400asa 35mm - preferably Kodak. Neither of the TWO local jessops stores could provide 10 matching rolls of any film (other than their own brand 200asa).
Retro are great and do next day delivery.