actually, I know I can't reach the window, I wondered what you thought of the layouts!

Bath with the side facing you on entry, toilet to the side of it beside the stack pipe and sink under window . maybe ?

I think the second layout is better and with the bath under the window the room will look bigger.
If you are worries about ventilation consider an oversized extractor- basically same vent in the ceiling but a big fan is put in the loft space above, then vents out of the roof. Alternatively consider building a box up from the ceiling to a roof velux- these can now be electrically opened.

but then you would need to put sink against left hand wall so you can have a mirror, is there enough space for that?

johnathandb1972, we have a loft conversion above (stairs are causing sloping ceiling at end near door) but could vent out the wall with the window.

Before playing with the layout, understand that you are dependant on where the plumbing goes and can go. If you are talking about moving the soil pipe for the toilet, is it actually possible? Moving a toilet and the associated pipework is not always easy, and it's not a case of i'd rather have it somewhere else, usually, it has to go where it is.

Re the extractor fan idea- even with a room above this is possible but the fan would be further up and the vent would travel through the room above. This idea now seems complicated (although not impossible) and assuming there is a room directly above the bathroom and no eaves space you would probably get the best extractor you can buy(or two) and go through the outside wall.
Lastly you might decide to swap the sash window for an alternative that looks the part but has a different opening (perhaps at the bottom).

man about the house, we can move the toilet as I checked. Johnathan, the window is recently replaced so will have to stay. I can open the bottom bit though, it's upvc sash lookalike. I suppose with enough ventilation we won't need to open the window so it's a bit of a non issue.

Hi Jodg, may I ask where you are based? Our showrooms offer a free no obligation 3D design service, which is a great way of helping customers visualise their final bathroom. A 3D design can really help when deciding where to position bathroom furniture and how the end result will look in relation your window issue. If you are local to one of our showrooms, all you need is your measurements and product specification and one of our bathroom experts will plot it all out for you so you have a clearer plan to look at.

I would leave it as it is. It gives a feeling of more space as it is.

I prefer the bath under the window. It looks better otherwise the room will look too long & narrow. You can always stand in the bath if you need to open the window! Presume you're not planning on having a shower over the bath?

Thanks for the extra comments. We have decided to go with the bath under the window and work starts on Monday! My only stress now is what to use in the walls. We don't want tiles so are going with shower board, except I don't like the trims...

looks like you are having a shower over the bath? in which case I'd stay away from the window and swap sink and toilet

A similar example of something we did previously but without the window and with similar sizes to yours. The loo can't be seen but is next to the photographer and was wall hung to give an increased sense of space.

drfeelgood10, that's what we are doing but toilet near bath because of soil pipe position and to allow access to an under stairs storage area which is next to the right of the door.