In terms of commuting, there are a fair number of pilots who do so from all over Europe on the 737 fleet. I don't personally know any on the 787/756 who aren't part time but having seen the 787 rosters, yes it is possible. Generally 3 to 5 days off between trips. Perhaps a 78 driver can chip in here.
Winter on the 737 is very easy going. 200-250 hours over 6 months (November-end April). All Canaries or Cyprus, so really coming into work once a week sometimes less. Subject to change but nothing has been mentioned by the company about using the Thomson 737s in Scandi-land during the winter. So far the balancing of winter work is all done by the 767/787. Busy summers, but nothing harder than I did at my previous company.
London basing is quite easy at the moment judging by the latest bid results. Very junior pilots moving south. LGW is to have 2 more 737s for Summer 18 too. Company will do their best for you, but it's all down to seniority and where they need people.
Anyone thinking of jumping from an Irish LoCo will not regret it in the slightest. It's simply a brilliant company.