if you get quotes via Moneysupermarket, they quote up to 16 years - you can get an annual Green Flag policy covering UK & Europe for about £65
once you go past that age limit, best is probably one of 2 options: add breakdown to your main bike insurance or take out a bank account with Nationwide for £18 a month (other banks have similar cover).
https://www.nationwide.co.uk/current-accounts/flexplus/
The latter is especially worthwhile if you have a wife/partner and/or multiple vehicles, including motorhomes up to a certain size. Even better if you can use the travel cover (subject to passing the health screening and paying any additional premium) and gadget cover. The extra cost for existing medical stuff rules it out for me compared to separate policies elsewhere.
If you switch to Nationwide from another bank, they are currently paying a bribe of £175 which covers a large part of the fee in the first year.