Genuine canister is about £35 if you have to buy one yourself or you can buy a tyre inflator and sealant can for under a tenner that will do the job. However Motability should replace it for you. https://news.motability.co.uk/everyday-tips/what-should-you-do-if-you-get-a-puncture-while-driving/ I bought an Airman Req Pilot for my own car a couple years back from Euro car parts. Cost about £25 for pump and sealant, with replacement sealant far cheaper than manufacturers branded stuff. £30 on Amazon currently!
Thanks. I’d need the £35 one on Amazon as the £30 only covers up to 17” rims. I’ll need to check whether I just need the canister or a new inflator as well. I’ll call Motability and BMW and see what they say. I’ve got until Tuesday to get something before we go away.