You may be under the impression that a simple Will is so simple that anyone can write it, particularly if you shop at WHSmiths.
However, the subtleties which ensure a Will is valid, are not necessarily apparent to the untrained eye.
Most Wills & Probate specialists will be able to spot the difference between a Will which is likely to sail through the Probate Registry, and one which is not.
Why give your family the stress of whether those deliberate mistakes will be spotted or not? Get things done properly and professionally, then breath easy.