I've seen situations before like this where it sometimes seems that you end up in a lose:lose situation - the PIL come to your house and in order to be polite to them you let them take control/do the cooking/etc - but then when you go to their house you are also expected to be polite as a guest and let them be in control, let them do the cooking etc etc...
I'm also 
about having to share a small living space with PIL for 5 weeks - not sure I could have have shared for 5 days with my PIL or even my Parents - particularly with a young baby and the different culture and language difficulties in the mix. If you're somebody that likes their home to be their sanctuary and you're not used to having long term guests then I think it is very easy for others that do like it or are used to it to underestimate quite how stressful the experience can be. Particularly the hours during the day when DH is at work and you'd normally be happy pootling around doing your own thing, and suddenly you have a load of extra stress and work and people around and it's horrible but bearable for a day or two - but can begin to get a lot worse and worse as time wears on.
And I wouldn't even be able to escape from it by taking the baby and going out - because I'd be worried about what they were doing back in my house - were they poking around looking at stuff they shouldn't, or throwing stuff away trying to be helpful by clearing up, or rearranging things to their way of doing things rather than mine and so on (I've had my mum, aunt and mil all do these when they were staying - and for only a day or two - and that's generally getting on well with all of them, asking them not to meddle in stuff (albeit phrased more nicely!) and sometimes when I'm there too, not just when I'm out.
If your MIL is somebody that wants to take control, but you don't want her to have that control, just remind her with a smile 'Don't worry about that MIL, you're a guest, relax and I'll cook/do whatever I feel comfortable and I'll just ask for help if I need it'. Or just remind her that she's in the UK now (I assume!) and that 'this is how it is done here. You can show me how you do it when I'm in your country.' Treating Thinking of them like toddlers too can be helpful - lots of 'don't be silly's' and 'Oh we don't do it like that here, look this is the way that works best...'
If you try to do it with a smile and be nice about it, it will be much more difficult for them to argue against and more importantly, it will be more difficult for your dh to go against you and side with his parents (which it sounds like he is setting you up to expect by telling you his mum is controlling) or to get angry at you. And next time your dh tells you his mum likes to take control remind him that that's fine in her own home but you expect that if she is a guest in your home then you are the one in control - and it's your home, your baby, your rules - particularly if he is not going to be around for more than half the time.
And it's a bit late to blame things on pg hormones - but hey - if you do need to then if they are annoying you or doing things that will cause a problem - then why not just blow your top at them if asking them nicely to do/stop doing something doesn't work? And if things are getting bad then send texts or emails to dh to make him realise there is a problem and it's getting worse so it doesn't come out of the blue. Plus next time you'll have a record of it so you can make sure that he only invites his parents for the time he has available to take off for them, rather than expecting you to host them for so long. I think it's really rude of him and them quite frankly to expect to visit and stay when he isn't around. So I'd be making sure that your dh is making sure his parents know how to behave too rather than to placate them by expecting you to give in to everything - it's a compromise all round situation.
I hope you've got a tv in your bedroom set up so you can escape to it if you need to feed your baby - that used to be my lifeline. Not so good if you have sky and the other people in the house start to change channels though! Are your pil used to watching tv at home - will they want to be able to watch tv at your house and is that possible (or something that you could set up before they come) - might help to act as something that they could do that would take the pressure off you from having to 'entertain' them!
Good luck - I think YANBU to want to be able to set some ground rules and ensure that you don't have a miserable 5 weeks, but I do think you need to think how you can do this in the best possible way to make things run smoothly and at least initially by making sure that you don't put too many backs up!