Have you googled it.
This from Colchester home brew forum.
After a fair bit of experimentation, I have settled on the following recipe which, though still not quite Abbot Ale, produces a very tasty beer:
For 23 litres
Grain Bill (Mashed in 12.5ltrs at 65°C for 90 minutes):
Pale Malt (5 EBC) - 4750g
Crystal Malt (130 EBC) - 250g
Amber Malt (100 EBC) - 50g
Main Boil Hops 90 minutes
First Gold (8.3% AA) - 11g
Challenger (7.5% AA) - 11g
Fuggles (4.8% AA) - 11g
Late Boil Hops for last 15 minutes
First Gold (8.3% AA) - 7g
Challenger (7.5% AA) - 7g
This produces a beer of around 4.8% ABV, with a bitterness of 30 EBU and a colour of 20 EBC
Obviously, if you are working in lbs and L/SRM measures for your grain or using US gallons rather than Imperial gallons or litres, you'll need to adjust this accordingly.