Postage rates rise on Monday March 25th 2019, so you might like to buy in a stock of stamps of the “non value indicator” type which will hold their relative value. We have done it already by ordering online from https://shop.royalmail.com/ which is currently offering free delivery on orders over £50.
It costs nothing extra to order a great variety of colourful stamps. We advocate that every business does a little bit of direct mailing, for example in its slack season. Our standard stamp for direct mailing is the grey-green second class “English country definitive” with the three lions. This is an attractive-looking stamp and it does not scream “second class” at the recipient. The same can be said of the nice blue second class Scottish country definitive.
For the other mail we send out, we use a variety of nice stamps and commemoratives and we can order in early March in order to stock up. We often get our own envelopes handed back to us with signed documents in them, so we cut off the used stamps and give them to charity. Everybody wins.