I would say dont get too hung up on the contract not including rent - it could just be the way the salary is divvied up. For example, say my salary in my previous job was Dh1,000, it was divvied up as Dh600 salary, Dh100 car, Dh100 mobile phone, Dh200 rent. Whereas in my current job, it is simply Dh1,000 and divvied up as Dh600 salary, Dh400 'additional allowances'.
I agree with a lot of what other people have said - that the cost of living is high, regardless of how much you earn. School fees are a huge factor and even if you get an education allowance, there's a good chance it won't cover the full amount. Also check if your husband's contract covers flights for the whole family - a couple of trips back to the UK each year soon add up.
Rental prices are falling - in my opinion, housing and utility bills are one of the things here that are quite reasonably priced. We live in a lovely community with lovely pools, parks etc and our house has 3 bedrooms, a big playroom, laundry room etc and we pay Dh125,000 a year - thats around 26,000 GBP a year, so just over 2,000 GBP a month, which is a loooooot less than we were paying in London for somewhere much smaller.
You didn't mention (I don't think) if you work or not but part time work/flexible work isn't really a concept here. So if you do work, you will still need to think about things like school buses and wrap around care.
Feel free to shout if you have any more questions - we've been living and working here for 10 years and both my kids (3 and 1) were born and are being raised here.