1 - Use TLC Direct.
2 - Use EBAY, might really be "new-fitted-removed" but ok.
3 - Use PayPal, the seller never gets to see your card details.
PayPal has some downsides. Buyer protection is imperfect, they are not a bank so do not leave large amounts with them, they are USA + USA managers + India programmers however have proven reasonably reliable. PayPal has some upsides. The seller never gets to see your credit card details, you do not need to register (link) a bank account to it and I recommend you do not. You can delete a credit card as necessary, or keep a card separate for PayPal link purposes. You get an online receipt, I can bring up receipts going back to 2003 and I have 120,000 transactions. You can download PayPal history in comma-delimited format which Excel will import without any problem at all (as well as e-finance software).
If you are concerned about online credit card fraud, and you should be, a simple tip is to have a separate card which is exclusively for online purchases with a low credit card limit. MBNA for example will permit a credit card limit down to =A3100, a figure of =A3500 or =A3800 is probably more practical if you want to buy a washing machine online from JL. A credit card provides valuable protection and should not be overlooked - never ever use cheque. Do realise a debit card provides similar protection incidentally.
A credit card provides protection where a) any line item is over =A3100 (but NOT where you buy 100 items of =A31) and b) for the whole purchase where at least =A3100 is paid by card (ie, the value of a car where you pay =A3100 on C/C).
Credit card companies are used to fraud and handle it reasonably well. I have had 23 cases of credit card fraud running a web business (a lot of places including competitors have my card details). Each time the card company just re-imbursed without issue, it does however require a signed-for reply to them confirming the fraud and in any case for your own records so realise you need to queue at a post office for the important franked signed-for label & till receipt. Those frauds totalled over =A328,000 and would have been higher had the "floor limit" not been triggered in some instances (which also usually requires goods be sent to the card holders registered address only minimising unrecoverable losses).
The downside with credit card is many companies, such as Citicards, will not honour protection if they can find any loophole and that often includes foreign transactions. So beware ordering online from another country, you can very quickly go past their 90day / 180day limits if you have to send things back by surface mail and refunds get dragged out.
I shop almost entirely online, and actually prefer PayPal because it provides an online receipt - obviously I print off to PDF and have the C/C statement one also. It is very useful to be able to prove a) what you bought and b) what you sold online going back far beyond what the tax office requires (6yrs in theory, in practice there is no strict limit if there is sufficient fraud).
MK outdoor sockets are good, but shop around on price - B&Q do them, Screwfix do them. Ebay is good IF you can actually get new (ask for a photo of the screws, that usually gives the game away re "new" and "sat on a wall and they want the money back" :-) White can often be cheaper than grey as it looks ugly unless a noddy house (which itself looks ugly so the problem is less material :-)