Hi Bandit650,
I would say P-T-G & low n' slow offer good advice, at the end of the day as a new f/o in a uk 'lo-co' even at low hours you are still worked in the same roster pattern as your experienced colleagues, therefore you get the same time off as a regular line pilot. Plus of course you will still be restricted by the same flight time regulations & limited to 900 hours flying at the end of the year. So generally in a uk 'lo-co' you get quite a few days off per month in the roster pattern.
I found that although you have quite a reasonable amount of time off as a new pilot, flying the early flights online you need to have your head in the books at all times, getting very familiar with ops manuals, reviewing tech manuals & just generally trying to get to grips with the additional knowledge required to successfully operate an aircraft on a regular basis.
Social stuff is pretty much similar really but as P-T-G quite rightly points out forget being around for bank holidays/xmas/birthdays/weddings/weekends!
I personally prefer the variety of shift & pattern work as I hated the 9-5 Mon-Fri grind with everyone else, I prefer to have days off during the week occasionally.
In general you work the same hours as a normal line pilot when you are a fresh f/o but be prepared to work outside of line flying hours in order to make your life easier at work!