Loft insulation and a new boilers - are there grants for both?

[KatyMac]

First time buyers know they need loft insulation and a new boiler so are trying to work out which is eligible for help?

The boiler might have to wait until.next yesr but the insulation (plus heavy curtains) are a "as soon as we move in" job

Can they get any help?
Does it matter if they buy different types of leftover insulation from facebook and do a patchwork?