Ericaceous compost. Can I make my own?

The short answer is yes you can make your own but ideally you need an accurate testing kit to make sure the pH is correct for growing acid loving plants.

Leaves and conifer chippings alone will not really give enough acidity and the wood chips take a long time to decompose. Pine needles are quite acidic but the best thing for growing blueberries is peat...it's their natural habitat.

I've seen liquid feed for acid loving plants, and if I can't get a result next year with tea, pine needles etc, I'll give it a whirl!

At Askham we top up our ericaceous beds with leaf mould, to keep a low PH, so yes, it could work

the question is how long are you prepared to wait to get the volumn of compost you need.
The easiest option is to buy ericaceous compost if its just a small bed and you'll be up and running straight away.  You could also make you own ericaceous by mixing bog standard peat based (which is cheap) and mix with a few bags of garden Topsoil.
If you have a BIG area to cover buy in a cubic metre of good quality topsoil/loam (Rolawn is a prorpriety make) and mix with a bags of Irish Moss peat.