Will
Whoever told you that you cannot appeal after the MR stage is incorrect but you do need to be aware that appeals are taking nine or more months across most of the country.
While you wait for your MR to complete you can claim JSA but if your area is now UC only then you should get advice first as once you claim UC you cannot return to a legacy benefit such as ESA.
If you are able to claim JSA then once your claim is accepted and in payment then you can present a Fit Note and be excused from any Claimant Commitment for up to 13 weeks.
If you have to appeal then you can come off of JSA and ask to be paid the ESA Assessment rate while you wait for a hearing.
Any MR or appeal is going to need you to show that you meet the ESA criteria for an award, our ESA Claim guides list and explain this see
www.benefitsandwork.co.uk/help-for-claimants/esa1 Gordon