Me I would just let Openreach install it by the front door, then when they have gone sneakily install a length of simplex APC SC-SC cable to where I wanted it using whatever route I fancied and used a APC SC-SC simplex coupler to join the two lengths together at the front door.
It will cost more for the shipping than the parts, for example at fs.com a 30m length with a 10mm bend radius will cost £5.40 and the coupler is 44p. You can of course get it made up with whatever length you choose.
https://www.fs.com/uk/products/41922.html
https://www.fs.com/uk/products/48491.html
however shipping will be £9.24 inc VAT.
I am sure now lots of people will wibble about not doing it etc. as it's technically not allowed. However as long as you are prepared to move the ONT back to where Openreach had it in the event of an issue don't frett, it's no different than having to test at the NTE5 master socket with a copper setup. Just don't loose the dust caps so you can stop the ends getting contaminated if you need to disconnect. stuff.
A lot of people seem to think that fibre optic cable is some sort of magic snowflake that requires a certified wizard to do anything with or it will break. In my experience (15+ years now working with it in data centres) while more delicate than copper it's not remotely fragile, especially the newer tight bend radius stuff like linked above.