Ok so it looks like the move will be on towards the end of November to L'Isle Adam.
Need to sort out a bank account and mobile phone.
If anyone can recommend banks and phone companies that they have found to be good would be grateful
You'd need the bank account sorted first, but I can very much recommend Free for the mobile phone. Or else take a look at one of the other "cut rate" phone services: Red, Sosh, BandYou and I think there is one other. No muss, no fuss - and certainly with Free, you can handle everything by Internet - they'll mail you your SIM and away you go! (Also, no contract - so you can change after a few months if you find a better deal.)
Unlike the UK where branches are "all the same" French banks depend a lot on "le directeur" ( bank manager). Also the big brand names (Credit Agricole, CIC etc ) are actually groups of regional banks, so there is less "sameness".
I suggest that you find a bank close to your home or work and try that. When I first came to France I used a small branch of CIC in a small town. They were very helpful and took time to explain the Fr banking system to me. I also took out mobile phone, car, health and house insurance with them, because with "not so good French" it's easier to talk person to person than through a helpline.
A lot depends on your conseilleur allocated to you.
Banking - I was able to set up a French bank account with HSBC before I arrived, and linked it to my UK account. This is extremely helpful as it makes transfers between the two very quick and easy and meant it was already set up before I got here. There are not many HSBC branches around, and my branch is technically the international branch in Paris (nowhere near me!) but I can do everything online and on the phone. If need be, they also speak English.
Mobile phone - I was going to go with the budget, online phone companies mentioned above (Free etc.) but then I also needed internet, TV and landline phone. These tend to come all bundled together and you get pretty good value if you get it with the mobile phone contract too. I went with Virgin, who have a good package for only E30 per month, including everything. The mobile gets 120 mins calls, unlimited text and a bit of internet. The landline has free calls to UK landlines and we get the standard French channels, plus some international news channels. I was also able to get another sim card for a mere E1 per month for my other half, with 60mins and a good number of texts. I understand that Ffree offer fairly similar deals, but they weren't available in my apartment for some reason.
I used B&You for my two years in france. the coverage comes from bouygues, their plans are well priced and you can call and text long distance to many countries around the world free. As a canadian with a close family at home, this was really important for me in france. It was also really easy to cancel once i was going back to canada. No need to send a hand written letter stating you want to end the contract. You just check a box on the website and input the date when you want to stop the phone plan and you're done. I will be using them again when I go back to france for sure.
Mobile phones. There is absolutely no need to commit to a contract. Every major supermarket chain sells unlocked mobiles, some of which are unavailable in the Uk. They also sell PAYG SIMS. Leclerc's service is very good and piggybacks off Vodafone. Running cost for this is about 1.5E a month and I have an auto top up setup so as I never run out of credit. So as I can be available to those in the UK I have a dual SIM phone, both of which can ring at any time. I do have to be careful which SIM I call from though otherwise I end up making an international call. For occasional use a 3G dongle is great too, they tend to remain valid for a year or longer and can be reactivated easily on line.
Banking. I echo others, it is not the same set up at all. It can be impossible to pay in a cheque in a branch in a neighbouring town because the banks may have the same name but they are in different regions. Also your allocated conseiller will become your best friend because they oversee all your major transactions so treat them well. Charges are higher in the Uk.