There are two government driven initiatives available today for help with costs of insulation. The Green Homes Grant, a direct grant given to you in the form of vouchers, administered by UK government, and the ECO (energy company obligation), an indirect grant given to your installer for carrying out the works, administered by Ofgem. It is not possible to use both grants to fund the same measure, however, it is allowed for a household to benefit from both grants, for example one funding roof insulation and the other wall insulation.
For most households in the UK the Green Homes Grant grant will cover up to 66% of the installation of specified heating efficiency measures, including insulation, up to £5,000, for households on low income this can rise to 100% up to £10,000. Vouchers to be spent with qualifying suppliers can cover material, installation and VAT. Most UK households will be eligible for the grant apart from original occupants of newly built homes. Eligibility details, additional information and how to apply can be found here. Be aware that vouchers agreed must be redeemed and the relevant measures installed by the 31 March 2022.
Fewer households will be able to take advantage of funding through the ECO (energy company obligation). The initiative is aimed to help those in, or at risk of, fuel poverty. To qualify you will essentially need to be enrolled in the WHDS (warm home discount scheme) or be in receipt of certain benefits for the lower paid. It is important to be aware that being eligible does not mean anyone is obliged to fund work for you. If you are eligible measures may be funded by one of the obligated suppliers (most major energy companies) who can be contacted to discuss what is possible. You do not need to be a customer of the obligated supplier you contact. Eligibility details, additional information and how to apply can be found here. You may be contacted by an installer claiming to work under the ECO scheme and if so it is essential that you verify their credentials. They are only able to do work under the scheme via an obligated supplier.