Thanks for the responses.
It's not an expat package, it's a 'local hire' equivalent - same company but different office, if that makes sense? DH and I (it was a shared dream, I'm sure it was, since almost day one of our relationship), always hoped to relocate here 'one day' though had hoped it would be with younger DCs.
He's not making loads less than his colleagues, just the ones who keep a flat in the city!
I have met his colleagues, it's a small office in a big building - just six of them, all men. When we came out for DH's interviews - I came too, to meet people and look at areas - his colleagues took us out, it was great fun but it was just the two of us. Stupid of me. Their wives are not around. I was 'one of the boys' when we were out - DH's future boss 'hilariously' ordered me a quadruple vodka and tonic, I thought it was friendly joshing(!) so stupid. And of course this is the world DH spends his evenings in.
There was a lot of talk about company bbqs and get-togethers, which DH reminds me of when I complain (I do complain), about him being out so much - that he needs to make friends with his colleagues and in the wider context (his company are part of a larger company). Apparently by summer it will be get-togethers all around.
The problem with the DCs school is that they are bussed there. I could get there under my own steam but it would take over an hour, or I could get a cab. I have asked about being involved as a classroom helper and there is a system in place but I need to be checked (like CRB check but specific to this country and district), and of course that's a huge palava and I don't even have half the paperwork I'd need to submit yet.
In the UK things were different, of course. I didn't go out much even then but I could've, and I had local friends and people to say hi to (DCs friends' parents etc), took the kids swimming, we were five minutes away from the high street and cinema. I saw my friends regularly but more importantly they were just a facebook message or a sms away and I didn't realise how helpful that was.
DH had a lot of activities even then, often with the DCs which is the case here too but it feels different. For example, he and DS1 both do a martial art. In the UK they went to the local sports hall (5/10 min walk), on a Tuesday and Thursday evening to train and we'd have a pizza or something else quick when they got back (younger DCs in bed). I could do stuff easily 'for me' in the daytimes - see a friend for lunch, go swimming.
I think I could be helping myself more. I have been SO miserable it's sort of fed into a feeling of hopelessness. I also feel guilty that the DCs seem not to have made local friends yet. Again apparently everything is different in summer (very cold here atm). I could INSIST on us all going into the city on the weekend and doing something together - I think I will - and I could get a cab to the nearest gym once a week and hang the expense.
I do talk to DH about how I am feeling - I try to be more constructive than I was in my OP - but he gets irritated with me.