Can't do an initial JAA Class 1 in Dubai but you can do a renewal. You'll have to get the initial at the Mater Hospital in Dublin or CAA House at Gatwick in the UK. However the good news is you can get an initial FAA Class 1 in Dubai. Dr Akel's Clinic is the place to go. Located above Magrudy's on the beach road. Phone 04 3494880.
As for Schools in the UK or Ireland for that matter, do a search in some of the other Forums. As I suggested earlier there is a possibility of getting a JAA licence through a school in the States which in the long run will cut costs.
As for getting in to Aer Arann with just a frozen ATPL, no idea but a lot of companies want people to have experience (just look at EK, they want you to have 2000 hours jet let alone the 4000 hours total) and getting that can be interesting. I went the Flight Instruction Route and then flew Cargo at night. Others go the charter route in piston singles and twins out of places in Africa. There are many Avenues, its up to you to choose.