The following regulations are generally not exclusive to lighting, but have to be complied with if you are selling or offering to sell lighting products.
At present, EU and UK legislation is the same as far as requirements are concerned, though differ in terms of bodies etc. Differences are given under each section, and a table of UK/EU equivalents is given in UK and EU equivalents.
Low Voltage Directive (LVD)
Energy Labelling - it used to be that lamps, as well as lamp bulbs, needed to have an energy efficiency label (e.g. going from A to G in energy efficiency). This is no longer required for lamps, but is required for bulbs.
If your lamp incorporates Wi-Fi, Bluetooth, Zigbee, 3/4G or similar, then you will need to comply with the Radio Equipment Directive
Also, for all products, there are the Directive 94/62/EC: Packaging Regulations. Like WEEE, this is implemented at the member state level, so requirements vary according to the country you are shipping to/in. This has also been implemented in UK legislation, but in a way that small producers are not affected by it.
A Declaration of Conformity must be created to certify that the lamp complies with the relevant legislation. The information to back this up is kept in Technical File by the manufacturer.
Templates are given below (in Word .docx format), for you to modify to meet your needs. The EU one is for use in all EU member states plus Northern Ireland; the UK one is for use in the rest of the UK.
UK - Class I and II
UK - Class III
EU - Class I and II
EU - Class III
This applies to second hand lamps. If you are upcycling, repurposing or otherwise converting something into a lamp, for example a wine bottle, then this counts as a new product, and all he standard rules and regulations apply.
If you supply or sell second-hand electrical equipment as a business, it must be safe and meet the requirements of The Electrical Equipment (Safety) Regulations 1994 (see GPSD). There is no specific requirement for safety testing in the regulations, but to ensure the equipment is safe some form of inspection and testing will be required, and doing a PAT test is the obvious way to do this.
Older plugs (pre 1984), without the sleeving on the live and neutral pins must be replaced. Plugs and fuses must have an approval mark: ASTA Diamond Mark, BSI Kitemark, or Nemko N Mark - so older ones without this may need replacing. Re-wirable plugs must also be supplied with wiring instructions, usually on a card over the pins or on a tape around the flex. The cores within the flexible cable must use the standard blue, brown, and green and yellow colours.
Second-hand equipment is not required to meet the CE or UKCA marking requirements and does not need a Declaration of Conformity (DoC).
UK guidance on selling second hand electrical items: https://www.businesscompanion.info/en/quick-guides/product-safety/second-hand-electrical-goods