If you are considering using aluminium windows then ensure they are thermally-improved or thermally-broken frames, standard aluminium windows conduct a huge amount of heat into and out of your building, decreasing comfort and increasing running costs. Timber windows and thermally-broken aluminium windows are similar in terms of thermal performance. Well painted timber windows should be maintenance free for 10-15 years, yes they will require more effort over time than aluminium but it is not a weekly event. This is still a major factor for many people in making this choice. Accoya timber (have a Google) is relatively new but does appear to allow a painted finish to last even longer. Double glazing, yes it costs more but not twice as much. If you buy good quality frames why would you not also buy good quality glass (and vice versa). It can be relatively easy to replace the single glazing in your existing frames with double glazing although this depends on the frames themselves. These are probably the largest areas of glass in your home, if you use single glazing you will lose more than 50% of your heat through them (depending the level of insulation in the remainder of the building, possibly more) hence choosing the right glass is incredibly important. Building comfort is a product of many many factors, each decision contributes to the whole. Be mindful of 'death by a thousand cuts'. I hope this helps a little.

Both so close it doesn't matter. Aluminium is better if it's thermally broken.

As mentioned by Kate and jo wst, a single door with glass panels might be ok, with a side window. But, I still think that if your clothes line is not on that side of the house, it is probably quicker to walk through to other exit. In my previous house, that was the case. And with the boundary fence, only giving a small walk way along the home, then it would be more comfortable to walk through the home. As previously posted. I had this exact scenario in my previous home. Never actually used the sliding door on a regular basis.

We have the same challenge with those cream window frames. If you use window coverings (I will probably add warm white blinds and sheers) think about what they will look like from the outside as well. Stark white will look wrong with our style of home. I love plantation shutters, but again, can’t have them because they’d look terrible from outside.