Can't help with recommendations Dan but paper rolls tend to come in 16", 24", 44" & 60" widths. If your "about" 60cm is actually over 24" (including any border you want) they will have to use a 44" roll which will increase the cost significantly. I've done a 9ft x 12" pano before on test paper (
link to post) at home, so a sub 16" print shouldn't be too bad. It will also depend on the paper choice too. Cheap Kodak paper will be vastly more economical than an archival paper but will likely fade over time and/or get scratched easily, especially if it's not behind glass.
A quick look at ThePrintSpace pricing suggests that a 24" x 118" print would slot into about the £172 mark on plastic Fuji paper and about double that for something archival (
https://www.theprintspace.co.uk/art-printing-prices/ - click on "panoramic formats") In all cases, I would get an A4 section of the print done first to make sure you're happy with colour control, sharpness and paper quality.
As you'd be spending so much money, I would also advise you to get in touch with them first (whoever you decide on) to sort out the submission as I'm guessing it's a rather large file.
ThePrintSpace also do mounting, whether it's a hard backing board, aluminium plate, or frame. It's gonna be expensive for something that big though.
I'm not an affiliate for them or anything, but have heard excellent reports. Never used them though as I print my own - it's significantly cheaper for this sort of work!!
Good luck in your search. I'm sure others will chime in with their thoughts.