Have you got friends who are gardeners? If so now is a good time to split things and I'm sure they could help you with a few bit and pieces. Also beginning of May round here is when the church fundraising plant sales happen where you can pick up decent plants fir not much. Google the secret gardening club , they sell in 3's and have free postage.
Like you I have one bed in sun and another in shade. Things are going much better now I plant for the conditions. Things that are doing well in the sun are Bowles Mauve perennial wall flower, sedum, penstemon, geranium Roseanne, roses, aster, dahlias, cosmos, snapdragons, lupins and I've just ordered some lavender from the secret gardening club.
The shade bed is newer . I found some, ferns growing in steps so transplanted them, foxgloves from seed, tiarella, geranium phaeum, hellebore, carex, holly fern, ophiopogon, astilbe, aquilegia, primroses and just ordered some brunnera along with the lavender.
Places like Poundland and Aldi are worth a go for plants. My £1.79 Aldi roses are doing well. If you have Amy Tesco Clubcard vouchers you can get a subscription for a weekly gardening magazine which often comes with free seeds. Make some paper pots from newspaper wrapped round an aerosol can and get some started on the windowsill. Ask friends for cuttings and see what you can get going in a jar of water on the windowsill - Rosemary is good for this and will do wel, in your sunny bed.
Stick a wanted ad on freecycle and see if people have things they can give you . Clematis vary in how vigorous they are, Montanasare one of the more vigorous ones. Don't plant too close to the fence (I'm guilty of this) as soil doesn't get moisture. Plant a bit forward and angle it back. If you can get hold of morning glory seeds they are annuals so will do well in a season.
I have cats and things that have done well chucking in seeds are aquilegia, nigella and poppies. Most important of all are regular cups of tea whilst you sit and watch the progress of your hand work.