In order to participate in the scheme, bike repairers are required to meet certain criteria, including carrying £2 million in public liability insurance.
Full terms and conditions can be found when registering for the scheme, which is done through the Energy Saving Trust website, and which set out what are and are not considered as “eligible repairs,” as follows:
“Eligible Repairs” means repairs that are:
necessary to make cycles roadworthy and fit for purpose; and
carried out on premises in England.
Eligible Repairs may include:
repairing or replacing tyres, tubes, wheels and related components;
adjusting, repairing or replacing braking system components;
adjusting, repairing or replacing transmission system components;
repairing or replacing other essential components which prevent safe use of the cycle e.g. deteriorated grips or saddle;
repairing or replacement of components for permanently fitted lighting systems.
The following repairs are not Eligible Repairs:
a sale of replacement parts without any repair work.
replacement or upgrade of existing safe and roadworthy components;
replacement or repair of removeable lighting accessories.
The terms and conditions also stipulate that the customer, having sourced a registered bike mechanic through the Energy Saving Trust website, will need to provide proof of address matching the voucher details both when they drop the bike off for repair and when they collect it.
When claiming on the voucher, the repairer is also required to ensure that is accompanied by a photo of the bike that has been repaired under that voucher and which must “be a photo of the whole cycle, including frame and wheels, be clear and unobstructed [and] correspond with the description of the bike provided on the voucher details.”
https://road.cc/content/news/details-emerge-governments-fix-your-bike-vouchers-274765#block-node-comment-block-node-comments
I don't think I will bother.