Fatigue is so common, I just finished my 6 weeks last Friday 05.07.2024, so pleased its over, I felt like I had been hit by a truck on week 5,
weeks 6 and this week post, I'm doing better,
But yes feeling so tired and fatigued is normal. just try and rest as much as you can. it dose get better, possibly check in with your Rad nurse about the nausea, I personally didn't experience that, but ginger is a good anti nausea remedy, so if you like gingernut biscuits you could try a gingernut biscuit with a cuppa. works a treat with sea sickness too.
Best of luck, hope you feel better soon