Most commercial thiocarbamide toners are more similar than dissimilar Gary.
As you are in the UK you will probably find Fotospeed most available. I use it often and it works well. Being thiocarbamide, you can also adjust the colour.
If you want to tone just the highlights, you need to bleach very lightly. You might want to dilute the bleach to get more control and repeatability. It's also a good idea to time your bleach stages and keep notes of the times you used as the bleach (and therefore the toner colour) has always gone further than you can accurately see.
Don't forget, warmtone papers bleach faster than neutral or cold tone papers.
Tim