Do you mean after the 6 months? Or was he bringing in more than his take home salary monthly somehow and that's where the £1200 gap is from? Sorry, just a bit confused about how urgent this is beyond him trying to secure another role in a similar salary range.
My sibling's been through redundancy a few times in the last decade due to the nature of their sector and they've managed to secure new (and better) roles within 3 months but it's been very stressful.
If I were in his shoes I would make sure my LinkedIn was up to date and in regular use and make sure I'm using my career networks. I'd be open about my situation and that I'm actively looking for work in a certain area. I'm sure his CV is up to date but if not, make sure it's amazing and if you've got any friends who work in recruitment or HR, call in those favours to check it over.
I'd let friends and family know I'm available and what my skills and expertise are.
A work contact has recently been through redundancy following a restructure and I and others in the sector have been sending her freelance opportunities, project work, consultancy things and she's managing to juggle those things which are relevant and interesting to her and her career while also getting a part time job to fill in the gaps. She was working on a project through her organisation and we've managed to bring her on that in a freelance capacity in another role so we don't lose her expertise.
As for ideas for cutting your outgoings, have you got a list of your monthly budget and do you usually go through your statements with a fine tooth comb to track spending? I do because my income's not massive and I need to stay on track. If you haven't, it's a useful exercise as it will give you the real picture, not your assumptions.
I used to think I spent too much on clothes and makeup but when I started looking into my spending more closely, that's not where I was going beyond a reasonable amount, it was more that I felt guilty when I made those purchases.
Mortgage holiday - you can but ask. Contact your mortgage lender to ask. I contacted ours during Covid as I wasn't sure about our income during that period but we were both employed throughout and didn't need to pursue it.
Are there any other repayments that you can pause for 6 months to a year? Car, furniture, loans etc?
It goes without saying but if you were planning a holiday, don't go. I've had to cancel our plans to go abroad in the summer as we've had to do some work to the house and there's no spare money for funsies. We'll go another time and enjoy our local beach (and redecorating our fixed house).
Do you have things you can sell? Get on Vinted.
Do you have more than one car? Can you get by without one? Especially if your husband doesn't need one for a commute maybe? My car is very cheap to run and tax and insure as it's tiny with a small engine and we bought it 4th hand in cash. I'm guessing from your income level that your vehicle(s) will be fancier, more expensive to run, tax and insure etc. Can you sell a car? Might be more complicated if it's a company care or on finance or whatever but it's a potentially large outgoing that can be cut.
Look at all your subscriptions on your bank statements. You will probably have some completely unnecessary ones that are nice-to-have but need to be cut if you're slashing your spending. Some might only be £9.99 a month but they all add up. You don't need Hello Fresh and the Week newspaper and that monthly craft magazine and the NT Online.
Your questions about TV - you don't need Amazon Prime AND Apple TV AND Disney+ AND Netflix AND the TV Licence. Use Freeview via your smart TV. More info on MoneySavingExpert about that.
Do you have gym memberships? Stop them. Go for runs for free and lift weights at home. You can rejoin when he's got a job.
All these things on their own aren't much but add it all together and you'll get closer and closer to closing that shortfall.
Are you on the very best deals for all of your utility bills and insurance? Get on MSE for more guidance or go check out some comparison sites.
Are you paying a lot of interest on e.g. credit card repayments? This might not have been a major issue for you until now as you could afford it but it might be the time to get a 0% interest card to do a balance transfer. Repayments will continue but you'll pay back less over time and depending on when the 0% ends, you could reduce or pause some repayments.
Same with any store credit, if you've got Next or whatever and you'd usually pay it off, reduce that down to the minimum until your husband gets another job.
It's different if someone's never ever going to have that higher income but for you, it sounds like you're looking for some breathing space.
There are things we've always done frugally because we've had to that you can do for the next 6 months or beyond which can also help. Not buying new but from vinted and charity shops, using boot swaps at kids' sports clubs. Not eating out, taking flasks and picnics. I've never had a cleaner or a gardener, always washed our own car - any services that you outsource which your husband or you can do need to stop. We don't turn the heating on, we put on a jumper or a blanket. Doing a Secret Santa instead of buying loads of Christmas presents.
Some of it's incremental but it all feeds the bigger picture.