@Blackjeans88
You need to ensure the advice you get is not only from a solicitor but from a solicitor in your local area. There is a lot of discretion in Family Law and outcomes can vary depending on the region.
I'm going to give you some caveats but feel free to go to the last paragraph. MumsNet is generally a good place to get moral support and a bad place to get legal advice. Most of the people on this forum are people like me who have experience of just one divorce unique to ourselves. You'll find the following characters regularly on any thread:
It Was Amicable: Quite representative of most divorces, they were able to agree on everything through mediation and the divorce sailed through, relatively speaking. 60/40 split in favour of the lower earner, a share of custody ranging from 65/35 to 50/50. Legal flaw: none, but you're probably here because mediation has gotten you nowhere.
Dogmatic Feminist: Every SAHM gave up a stellar career. Devout belief in the justified redistribution of income through spousal maintenance provided the recipient is a mother and regardless of the father's ability to pay. Also tends to believes mum should get the house and half the pension. Legal flaw: maintenance is based on needs and ability to pay, not sharing. Both parents have to be able to house themselves. The outcome must be fair to both parties. The dogmatic feminist ignores all of these legal principles because they think the compensation principle applies even in "small money" cases, but it doesn't.
Captain Self Help: The direct opposite of dogmatic feminist. Believes everyone should stand on their own two feet after divorce. No maintenance, 50/50 sharing of assets, weaker financial party should get a full time job and an extra job on the side. Legal flaw: again, the law just doesn't work this way. Most divorces are needs cases and sometimes one parent needs more than half of the assets. Spousal maintenance also features in around 16% of divorces although most of the time for a nominal amount, so it can't automatically be disregarded. Often it is worth bringing up because the claim is quite small rather than non-existent and can be capitalised for a few thousand pounds extra of assets.
I Want the Lot: Not divorced yet, really here seeking advice themselves. Often developing into a Dogmatic Feminist, but a male version exists as well. Generally early in the divorce process and still believe their life should stay exactly the same "for the kids" (that they benefit enormously themselves is just a happy coincidence). Other parent can become a bedsit dwelling money robot who never sees the children. Legal flaw: they might egg you on to fight fruitless cases in court because of their own lack of experience.
Mrs Left Alone: Ex is a dick who doesn't pay his fair share towards the children (often self employed and fudging the figures). Or ex is perfectly fair but Mrs Left Alone thinks he should pay more. Different circumstances but their advice is the same. Fight for at least 70% of custody to get the house, battle through CMS. Legal flaw: not too many, but their case could be very, very different from yours. If their ex is a dick they're doing the right thing. The problem is you don't know them from Adam and they could be in the wrong and using the children for financial game is a big moral no no.
Moneybags: Husband earned a megaton, she got the house, she got maintenance, she keeps his balls in a jar on the mantelpiece.... Legal flaw: big money cases are rare and most of the principles applied in them are irrelevant in needs cases, because needs principles trump everything else.
Bitter Bum: I can be extra cruel in my name and description of this one because it's probably the category I fall into! Typically came away from divorce with less than half the assets or had to burn through assets fighting for a fair share. In many cases role in the family was undermined because of claims by ex that they did less of the childcare than was actually true. Ex was normally an I Want the Lot. Legal flaw: a lot of them are higher earners who are still so pissed off that the courts in England are so generous to the weaker financial party that they still can't quite believe it. May well give you moral perspective rather than a legal one.
Pretend Family Lawyer: Knows the legal language, doesn't know the relevant law. Will misunderstand and then tell you about various legal principles that won't apply to your case. Some of the most dangerous are the ones who are lawyers but don't specialise in family law. Plenty of divorce cases out there where highly paid solicitors fought fruitless claims, like Goran Mickovski. Legal flaw: lots of bad advice!
With all that said, going back to your original question about a Mesher Order. Statistically rather than legally speaking, I think your odds are low because these orders are exceptionally rare these days, as in much more rare than spousal maintenance. Also, I've heard anecdotes that if they are awarded it's normally for a short period of 3-4 years for reasons such as children doing GCSE and A-Levels or to let a fixed mortgage deal reach an end. However, two caveats. One, it might apply to your case and only a local solicitor will be able to say (so get a 30 min free consultation with a local family solicitor who - and this is very important - is a member of Resolution). And two, when he looks at the equity split your ex might decide he wants one. The advice about you paying the mortgage is also generally true and he wouldn't earn enough to pay it and be able to house himself. Again, only a local solicitor will really be able to give you sound advice though.