well done robdob!
1) 12 mile commute shouldn’t be too bad, depends how bike friendly the A62 is.
just take it easy and add quite a bit of extra time (maybe an extra 30 minutes). I’m looking at occasional commute across manchester 18 miles, downhill to work and uphill all the way home!
2) they’re concrete or metal boxes with windows. People go there to work together. A bit like a shop, but without customers, having to stand up all day and limited tea breaks.
You’ll be fine, offices are great as long as there aren’t any politics involved and the group of people you are working with are nice.
Enjoy it.