if its in voluntary liquidation then it will be a liquidator appointed and not a receiver (technical but important difference). If title to the goods is yours (and this can be established one way or another in a number of ways) then it should be yours to collect. However, just going to get it is not always that easy or right. Where is it? Do you have a right of entry or will you be trespassing? The liquidator will need the opportunity to make sure it is not his so without this and proof he will resist any attempt to collect (which would involve the police/security). If he didn’t do that a lot of assets would just disappear.
The liquidator will not want to keep something he does not have title to (pay insurance, storage charges etc). For what my opinion is worth I would think getting evidence together(emails, delivery notes, your detailed versions of events etc) to prove it is yours – call the liquidator/his staff a lot (basically be a pain – it is just these peoples jobs and they will not be that well paid so you will need to make yourself a priority), give them the evidence and say you want to collect asap. And keep pushing.
As a slight tangent – as a creditor you should have received prior notice of the impending voluntary liquidation. Is it insolvent? i.e. Creditors’ Voluntary Liquidation? If it is a Members’ Voluntary Liquidation it means it is solvent and all creditors will (eventually) be paid in full.