If you haven't fitted M+ before then I'd be tempted to pay the bike shop price and get them to let you fit them under supervision/instruction. Or buy them online and fit remove a couple of times in the garage before you go out on them.
Having practiced with them, and Marathon winters, I can fit without levers or straps on all my wheels. If, or when, I do actually get a puncture in them then I expect the 'real' experience to be tougher, no doubt dark and possibly raining. Having had the practice I fancy I'll manage, without it I think I would fail.