Short answer: yes — surplus stock, ex-display items, returns, and office equipment you're replacing can all go to a charity shop rather than the skip, and if you're a limited company, it comes with genuine Corporation Tax relief, not just goodwill.
Per HMRC's own guidance, a limited company pays less Corporation Tax when it donates equipment or trading stock to charity. For equipment (office furniture, computers, machinery), you can claim capital allowances on the cost, provided it was genuinely used by your business. For trading stock, its value doesn't need to be included in your sales income, giving you relief on the cost of what you've donated. The donation has to be genuine — not conditional on getting something of material value back — and it's worth checking the charity can actually accept the gift before you commit it in your accounts. See gov.uk's own page on this for the full detail and current record-keeping requirements.
An office move or unit clearance often means sorting a genuine mix of donate/recycle/dispose decisions at once, on a deadline. That's exactly what hands-on sorting and collection help is for — the same service used for house clearances, just scaled to a workplace.