Something along these lines?

I am thinking of how to make the kitchen bigger going into that space? A separate utility/wc is a good idea though. Some of the store could be utilised too maybe we actually have a pantry built in there currently as it’s only about 3m from kitchen peninsula.
Thanks

With sewage pipe and loadbearing wall? Not worth the hassle, i'd say.

What if you shifted area of utility over to narrow the toilet going the other way then put utility in store? Then where the utility currently is have more kitchen cupboards to flow into existing kitchen?

Also not sure it’s a load bearing wall. It was the back of the original house, but it feels and sounds like a stud wall now.

Could you move utility and wc into store, remove all the internal walls in that area so you create a longer kitchen incorporating that space.

Wouldn’t fit and I use the store at front for bike storage and tools. I use around a third of it currently for a pantry

You could move the door to the utility to access from the dining room to get an extra run of cabinets in the kitchen. I suspect that would not resolve your dilemma as I suspect the kitchen feels enclosed and a bit cramped. Rejigging the utility and bathroom are going to be very costly and I’m not sure it will give you what you want unless you move both utility and loo right back toward the stairs and store and access the store via the loo. Those walls look structural and if the are the original back walls they are structural irrespective of how they sound - so costly to remove. A third and cheaper option would be to swap the dining and kitchen.

Thanks. We currently have the dining at the back as a kitchen diner and where the dining table is on the plan it is a snug/living area to utilise the fire. It’s a nice set up but would prefer not to have a door going into that space. The utility space originally was closed off but wanted to be able to access the back of the house from the hallway and have natural light coming through which is what we achieved. I might change utility space to a run of cabinets built in fridge freezer etc to tie in with kitchen and then move utility to store - if that works in terms of water etc.

Are there any tall units in the kitchen right now? (as shown in blue)

No because there wouldn’t be much space between those and peninsula. It is tighter than perception on drawing. I am thinking of making peninsula and stretch along wall 300mm longer and utilise cupboard space on back of the island for more storage.