And that’s how the rich get richer 
Pay yourself and the Mrs £11500 a year tax free ,
5k ‘loan’ each a year tax free and anything above that is taxed at 7.5% instead of paying 20% tax 
Its not quite a simple as that.
When you take a directors loan, you are effectively just moving funds from your business account to your personal account. You can pay it off any time. So say you get a parking ticket of £100, you could take £100 from your business account, pop it into your personal account marked as "directors loan". the next day after payday, pop the 100 back into the business account and you have paid back the directors loan.
However there can be extra implications for large sums of money; for example if you are moving more than 10k a year through the directors loan account; this is likely to cause a red flag. There is nothing wrong doing it; but such large sums of money could cause money laundering regulators to wake up and take notice, so youd better be sure you have done everything to the letter of the law. Anything untoward? They might force you to pay your company interest, or take is as wages and pay extra tax.
Also you don't want to borrow more than the post tax profits, that can be difficult for a lot of companies because you might for example borrow £3k in one quarter with the intention of paying it back by declaring dividends from the post tax profits, but the rest of the year your business drys up and the available profits cannot pay the directors loan back and your stuck with an overdrawn directors loan account which is really really bad. In extreme cases, you can be made bankrupt by your own company and possibly face criminal charges for embezzlement...the list goes on.
This is why you need a good accountant. I use a firm of accountants who are tax experts as well it costs around £1700 a year, and its well worth every single penny.