Probably even much more costly then buying 2-5lbs from a reputable online supplier.

All the work except scenting, coloring and adding a bit of other goodies is done for you when buying a M&P base.

Some reputable suppliers are Brambleberry.com, greatcandle.com and snowtopcandlesupplies.com.

I've done business with all three, not soap, but their fragrance oils, and a few other supplies.

Melt and Pour Soap:
Technically, all hand made soap is "Glycerin Soap." In many commercial soaps, all the extra glycerin (formed naturally by the cold process soapmaking method) is harvested out. Thus, all handmade soap is glycerin rich (since hand made soapmakers don’t harvest out glycerin in their soap).

In today’s market, the term "Glycerin Soap" is commonly used to refer to clear soap. Generally, the clear soap has extra glycerin added to it to produce a very nourishing, moisturizing bar. Glycerin is a "humectant." It draws moisture to itself; the theory is that if you wash with glycerin soap, a thin layer of glycerin will remain, drawing moisture to your skin.

Clear soap can be purchased in large blocks to be melted down, colored and fragranced, and placed into molds (or used to make loaves of soap to be sliced). This type of soap is called "Melt and Pour" and the artistry of melt and pour is called "Soap Casting." Melt and Pour is gaining in popularity because of its ease of use. There are no significant safety measures (other than basic common sense – don’t put your hand in the hot soap, don’t cut your finger off with the knife etc…) needed for soapcasting. Children can do it. It’s a great outlet for creative types.

You can also make clear soap from scratch. This method involves all the aspects of cold process soapmaking, but takes it a few steps further by adding alcohol for clarity and a glycerin and sugar mix to suspend and enhance the clarity. It is a dangerous process because of the alcohol vapors. If you wish to make clear soap (which will not melt down like melt and pour – it’s one pour only soap), please read "Transparent Soapmaking" by Catherine Failor. This is an excellent resource for anyone wishing to make clear soap from scratch.

So to answer your question, yes and no.... I refuse to make CP soap in my home, because I'd have to LOCK up the chemicals. I have very busy inquisitive boys. And once they learned that I had "cool" stuff..they'd wanna try it too. If I wanted to make my "own" soaps, I'd much prefer to buy M&P in blocks and enhance it, or buy soap to rebatch by taking CP soap someone else made, grating and adding more liquids and cooking it down to make a "new" soap.
But I don't need to, because I have wonderful friends who make it and send it to me to "test". LOL

I'm sure there are some places in the UK too.

Eek..I did just do some checking. Postal rates are harsh in the US, but not as harsh as it is to Thailand, even from Aus!!!

Life is good here..Happy Holidays to you too!

While you are toying with the idea of making cold processed soap, keep an eye out for the ingredients needed, like sodium hydroxide and other fats and oils, and see if it is plausible.
With CP soap, the biggest obstacle is getting over the handling of the sodium hydroxide. Then most everything else is a gradual learning curve with lots of experimentation if desired.

Good luck!