Our architect has been gathering quotes and scopes of work from the various consultants we need for the next part of our self build journey (RIBA 2-6) and the MEP and Energy consultants are quoting £7-8k for their part. We have no experience ourselves and understand we need specialists to create the electrical and energy strategy/ liaise with building regs etc but it just sounds like a hefty price to me.  Anyone been through this process got any tips? 

You often do not need a building services engineer for a house.  You could get an architectural draftsman to mark up electrics, bathroom firm to do layouts, MVHR supplier to do the design, UFH supplier would do similar.

What is included in the scope for these two. If it includes full Passive House work up and all the detailed specifications including drawings / schematics for all.the systems it might represent good value. But as @Mr Punter says you can go other ways for most things.

You are probably better shopping around for your quotes 

Our Architect got quotes of around 12 k for a consultant to prepare a flood report (Sequential) With much of the legwork being done by us 

We found an expert who ran rings around planners That did everything for £1800 

Architect's are very good at spending your money