Have you used your 2018/19 £11,700 annual capital gains exemption? Consider selling shares where the gain is less than £11,700 before 6 April 2019. In addition, if you have any worthless shares, consider a negligible value claim to establish a capital loss. You may even be able to set off that capital loss against your income under certain circumstances which could save income tax of up to 45% of the loss.
As far as Inheritance Tax (IHT) planning is concerned, all individuals have a £3,000 annual allowance which means that gifts up to that amount each year are exempt from IHT. If you have not used your £3,000 allowance from 2017/18 you can make gifts of up to £6,000 before 6 April 2019 without the gift being liable to IHT. Also consider making regular gifts out of your income to minimise the growth of your estate that will be liable to IHT. Gifts out of your surplus income are not subject to IHT if properly structured but obviously advice should be sought.