Quite often if you search for cotton jersey it actual contains a small percentage of lycra when you check the details.
I have bought 100% cotton jersey from Driessenstoffen but their selection is a bit floral for a man`s t-shirt
https://driessenstoffen.nl/de/producten/?q=katoen      Don`t be put off by them being Dutch, several people here have used them and not had any problems.

If you are prepared to try it you will find that fabric with a bit of lycra/elastane  will actually hold it`s shape much better and if it`s only 5% the fabric will still feel very natural.   
I`ve just bought some of this and it is really nice quality
https://www.ebay.co.uk/itm/Plain-Colour-Cotton-JERSEY-Stretch-Knit-T-shirt-Baby-Grow-Dressmaking-Fabric/283019983031?ssPageName=STRK%3AMEBIDX%3AIT&var=584301442366&_trksid=p2057872.m2749.l2649

The test square is right.
The instructions are strange - they say that if you are printing A4 you should select "letter" - there is even a comment that this sounds odd but you should still do it!
I might play around and just print one page to see what happens.

I am going to make this
https://www.ellieandmac.com/products/kids-pocket-henley-top-pattern

It claims to be trimless and that every page should touch the corresponding page against a dotted line.   This is working where each side edge joins, but at the top of each sheet there is a blank space of about 1cm which I am going to have to trim off to allow it to join the sheet above in the right place.
I`ve read the instructions for printing several times and am pretty sure I have done  it correctly.

It`s not a huge problem as it is only a child`s top with not too many pieces but I`d be interested to know if I am doing something wrong or if there is a fault with the pattern itself

@Acorn - oh right!  My fault then.  Will rectify

All sorted now.  Sorry for delay in renewing @Iminei

When I went away to college in 1973 my mum bought me my first machine and chose a Singer as she assumed it would be reliable - it was rubbish!

Thanks everyone

@Happymrsg I tried that method a while ago but I don`t have an overlocker and if you can`t finish the raw edges neatly you end up with bits that curl up and that can show when you wear the garment.
For me, applying the binding as a strip - much like you would bind the armholes on a sleeveless garment - gives a neater finish on the wrong side which lies flatter

To be honest if you just want cheap curtains and you can find the size you need you would probably be better off buying ready made - possibly buying longer than you need and altering them.

If you are able to spend more I've had good stuff from Terry's Fabrics online and they will send you free samples